1. Field of the Invention
The present invention relates to a side impact airbag, and more specifically, to a dual chamber side impact airbag with an integral vent panel and an improved method for making the dual chamber airbag.
2. Discussion
Side impact vehicle collisions have caused a significant percentage of vehicle driver and passenger injuries. In order to minimize these injuries, several versions of side impact airbag systems have been developed. Many of these variations have involved different locations of the airbag system and various sizes and shapes of the airbags. Typically, these systems are installed on the outboard side of a seat back, on the door, or on the A or B pillars of a vehicle.
In order to provide protection for the occupant, an airbag of substantial size which deploys quickly is desired to fill the area between the occupant and the vehicle interior during a collision. Rapid inflation is particularly important for side impact airbags where very little time is available between sensing an impact and deploying the restraint. However, traditionally the larger the airbag, the slower the fill time is for that airbag. It is, of course, desirable to have the protection of a large airbag but with the inflation performance of a smaller airbag. This can be accomplished by utilizing a dual chamber airbag with a vented panel or membrane separating the upper and lower chambers. Studies have shown that the impact of the occupant's head to the head region of the airbag occurs after the impact of the occupant's torso with the lower torso region of the airbag. Therefore, it is desirable to have an airbag that rapidly fills the lower chamber, and later fills the upper chamber as it is needed. By providing delayed pressurization of the upper chamber the airbag can achieve better performance by providing a more rapid inflation of the lower chamber.
One type of dual chamber airbag is filled by an inflator connected to an opening in the lower thorax chamber. A panel is provided between the lower chamber and the upper chamber. The panel includes a vent so that the inflation gas may pass from the lower chamber into the upper chamber. The improvement accomplished by such an airbag is that the lower chamber is inflated rapidly, similar to a small airbag, and protects the thorax of the occupant. The upper head chamber is then inflated. The inflation of the upper chamber is also rapid because it is inflated as the thorax of the occupant presses against the thorax chamber, thereby forcing more gas through the vent in the panel and into the head chamber. All of this occurs before the occupant's head contacts the airbag. The end result is an airbag with the inflation performance of a small airbag in the thorax region, where it is necessary, and a slower inflation response to the upper head region where the occupant's head contacts the airbag at a later time than the occupant's thorax.
Dual chamber airbags, similar to the one described above, are not new in the art. Two general types are available. One type comprises two separate airbags, a larger upper airbag and a smaller lower airbag. The two airbags are sewn together such that openings located on the upper surface of the lower airbag and on the lower surface of the upper airbag correspond with each other and allow the inflation gas to communicate between the two airbags.
The process required to make the dual airbag described above involves a great number of steps and a large number of parts. First, both airbags have to be cut and sewn together. Following completion of that step, the two separate airbags have to be aligned and sewn together such that the opening in each airbag corresponds with the opening in the other airbag.
Another type of dual chamber airbag is a single airbag with a vented panel separating the airbag into its two separate chambers. This type requires several parts and several sewing and assembly steps in order to arrive at the completed airbag. Using known design approaches, five pieces of fabric must be cut and a hole must be cut in the separator panel. The two lower pieces and the two upper pieces are then joined together to form each separate chamber. The two chamber sections are then sewn together and the panel is attached along the seam that separates the two chambers. This entire process involves the cutting and sewing together of five separate pieces with the added concern of aligning the many different seams. This is both inefficient and expensive, due to the part proliferation and extra processes required for cutting five pieces and sewing them together. As with any process requiring additional steps increased waste can result when the pieces have to be scrapped because the later sewn seams are not properly aligned.
In view of the foregoing limitations and shortcomings of the prior art devices, as well as other disadvantages not specifically mentioned above, there is a need in the art for a more efficient method for making a vented dual chamber side impact airbag that involves fewer parts and processes.
It is therefore a primary object of this invention to fulfill that need by providing a side impact airbag with an upper and lower chamber separated by a vented panel.
It is another object of the present invention to provide an airbag with the vented panel separating the upper and lower chambers such that inflation of the upper chamber is controlled by the panel, resulting in an airbag which offers more rapid inflation to the lower chamber and delayed inflation to the upper chamber.
It is another object of this invention to provide an airbag where the vented panel is incorporated into the side pieces of the airbag itself, and not attached as a separate component of the airbag.
Finally, it is another object of this invention to provide an improved method for making a dual chamber side impact airbag with an integral vented panel, involving fewer parts and processes.